The first experiment designed to demonstrate active space-debris removal in orbit reached the International Space Station on April 4, 2018 aboard SpaceX’s Dragon capsule. The RemoveDebris experiment, designed by a team led by the University of Surrey in the U.K. as part of a 15.2 million euro ($18.7 million), European Union (EU)-funded project, is about the size of a washing machine and weighs 100 kilograms (220 lbs.).
It carries three types of technologies for space-debris capture and active deorbiting — a harpoon, a net and a drag sail. It will also test a lidar system for optical navigation that will help future chaser spacecraft better aim at their targets.
“For this mission, we are actually ejecting our own little cubesats,” Jason Forshaw, RemoveDebris project manager at the University of Surrey, said last year. “These little cubesats are maybe the size of a shoebox, very small. We eject them and capture them with the net.”
“We are testing these four technologies in this demonstration mission, and we want to see whether they work or not,” said Forshaw, referring to the harpoon, net, drag sail and lidar. “If they work, then that would be fantastic, and then these technologies could be used on future missions.”
Some 40,000 space objects — the vast majority of which are defunct satellites and fragments from collisions — are currently being tracked by the U.S.-based Space Surveillance Network. It is estimated that some 7,600 metric tons (8,378 tons) of junk hurtle around the Earth at speeds of up to 17,500 mph, threatening functioning spacecraft, according to a statement from the University of Surrey….
[T]hese same means of capturing debris could easily be used to destroy or otherwise interfere with functional orbital assets [i.e, a functional satellite], most of which are not equipped with a rapid means of evasion or any other form of defense. To a harpoon, net, or drag sail, there is little difference between an out of control hunk of Soviet era rocket and an operational communications or reconnaissance satellite.
Excerpts from BY ALEX HOLLINGS, SpaceX delivers prototype space junk collector to the ISS, but the experiment has serious defense implications, SOFREP.com, Apr. 6, 2018;
This Space Junk Removal Experiment Will Harpoon & Net Debris in Orbit, Space.com, Apr. 6, 2018